The seedling plants should be planted 10m apart, while for budded/grafted plants it should be 7–8m apart. December–March is ideal time for planting. Square/hexagonal or contour systems (on undulating soils) are followed for plantation. The seedling plants are to be planted @ 100/ha, whereas vegetatively propagated plants @ 200/ha in square system. In case of hexagonal system, the number of plants are 15% more.
Training and pruning
Modified central leader system is most ideal for training since it provides very good strength to its framework. Trees should be trained on a single stem up to 1–2m, on which 5–6 scaffold branches should be retained at almost uniform distance spirally. Excess buds should be pinched during first year. Pruning is not being practised in our country, as almost entire plantation is of seedling origin, attaining giant size which makes pruning in later years almost impossible. However with grafted plants, pruning is practicable which can help increase the productivity and improve the quality. Trees of seedling origin receive some kind of pruning while harvesting by thrashing the limbs with wooden poles. It is however a crude method which needs to be modified.
Manuring and fertilization
Although walnuts are not generally being applied with fertilizers, for achieving higher yields of quality fruits, application of fertilizers is very essential. For Jammu and Kashmir areas, a dose of 250g of N, 60g of P 2 O 5 and 250g of K 2 O is recommended to 10-year-old trees.
Full dose of P and K and half of N is applied 2 weeks before expected bloom. Rest of the half quantity of N should be applied into 2 equal doses, 3 weeks after fruit set and during early July.
For correcting Zn deficiency, 0.4% zinc sulphate should be applied as a foliar spray.
Where staking is required, the plants need to be tied loosely to the stake to prevent wind damage. Water sprouts developing from the rootstock should be pinched back.
Generally walnuts are grown under rainfed conditions, but they need adequate water during 5–6 weeks after bloom. Inadequate moisture results in poor quality. Due to lack of plumpness of kernels, yield is reduced considerably. In absence of irrigation facilities, sod culture in conjunction with mulching helps in moisture conservation. However, if irrigation is available it should be applied at 1–2 fortnightly intervals depending upon dry spell period and water-holding capacity of the soil.
Walnuts are usually harvested when hull colour changes from green to yellowish with cracks or when splitting starts at suture from pedicel end.
Nuts should be harvested at PTB stage (when packing tissue turns brown). If harvested earlier, the hulls remain stick tight and under over mature conditions, insect pests harbour within the hulls. Vegetatively propagated trees can be sprayed with Ethephon (2 chloro-ethyl-phosphonic acid) (1,000–1,500ppm) at PTB stage. By doing so, fermentation of hulls can be avoided and hulling becomes easier.
For better nut recovery, the orchard floor should be cleaned and tarpaulin or polythene sheets may be spread on the floor beneath trees prior to knocking of the nuts. After harvesting, nuts should be properly dehulled, washed and dried. In case nuts are not dried properly there is every apprehension of mould development which impairs the quality of the fruit.
In Himachal Pradesh harvesting commences from August and extends up to last week of September, whereas in Kashmir walnuts are harvested in September.
Dipping of nuts after harvesting in Ethephon 2,000ppm solution at PTB stage reduces dehiscence of walnut hulls from 13 days (in untreated fruits) to 6 days, resulting in advancement by 7 days. After washing the nuts should be dried properly. The nuts are packed in gunny bags. After removal of shells, kernels are dried in shade and packed in wooden boxes.
( Citrullus lanatus )
Chromosome Number: 22
Watermelon is an important cucurbitaceous vegetable. It is know as tarbuj, tarmuj, kalinda and kalindi in different parts of India. Though it can be grown in garden land, it is a major river-bed crop of Uttar Pradesh, Rajasthan, Gujarat, Maharashtra and Andhra Pradesh. As a common summer season crop, it is grown from the lower Himalayan region to southern parts of India, Punjab, Haryana, Karnataka, Assam, West Bengal, Orissa, Himachal Pradesh, Uttar Pradesh, Tamil Nadu and Rajasthan being major watermelon growing states. An excellent dessert fruit, it is relished by rich as well as poor. The fruit juice makes an excellent refreshing and cooling beverage after adding a pinch of salt and black pepper. The fruits contain 92% water, 0.2% protein, 0.3% minerals 7.0% carbohydrates in a 100g edible flesh.
|Climate and soil|
Watermelon requires hot dry climate and a long growing season preferably with warmer days and cooler nights. It cannot withstand frost or very low temperatures. For seed germination, an optimum moisture and a soil temperature between 25°–30°C is needed. Similarly plant growth is optimum under 28°–30°C, while fruiting is better at 24°–27°C. Higher temperatures are beneficial during ripening. Arid regions of Rajasthan are best suited for production of quality fruits.
Watermelon may be grown on a wide variety of soils. Sandy loams are best for early crop, while loams have high-yielding potential. Alluvial river-beds are also good for watermelon. Heavier soils do not permit perfect root growth and hence only short duration varieties with smaller fruits are suitable. The soil should be well-drained and should have ample organic matter. It is generally cultivated in river-beds by making trenches and sowing in hills or pits. A pH of 6.5–7.0 is ideal.
A number of selections, varieties and hybrids are recommended for commercial cultivation. These are given below.
It is a mid-season F1 hybrid. The plants bear round fruits weighing 6–8kg each, light green skin with regular dark green stripes, sweet flesh (11–12% TSS) with crimson-red colour. The flesh gets granular when over-ripe. It performs well under south as well as north Indian conditions.
Fruits are somewhat round (oval) and weigh about 6kg each. Skin colour is light green with dull green stripes. The flesh is deep red, very sweet (11–12% TSS) and seed arrangement is such that its removal is easier. It is resistant to powdery mildew, downy mildew, tolerant to anthracnose and blossom-end rot. It stands transport and storage well.
It is a Japanese introduction with fruits weighting 6–8kg each. Fruits have striped light green skin and deep pink, crisp, sweet (11–13% TSS) flesh with small brown seeds. The fruits ripen 90–95 days after sowing.
It is a late-maturing variety having green, striped skin with individual fruit weighing 4–5kg. The fruits have yellow flesh, which is moderate in sweetness with large seeds.
Fruits are round with light green skin, thick rind and good keeping quality. Flesh is dark red-sweet with around 11% TSS. On an average, fruits weigh 6–8kg each and mature 125 days after sowing.
An American introduction, its fruits weigh 8–10kg. It has dark green, red flesh with moderate sweetness (8–9% TSS).
New Hampshire Midget
This is also an introduction having small fruits, weighing 1.5–2.0kg each. The fruits have light green skin with black stripes, red flesh, suited for home gardens.
It is a seedless hybrid having aborted embryos and false, rudimentary, least perceptible seeds. The plants are slow-growing with dark green foliage, short internodes and leathery leaves. The fruits are seedless, somewhat irregularly triangular, dark green with thick rind, crisp, deep pink flesh and excellent quality. It takes about 105 days to ripen. Costly and tedious seed production and difficulty in seed germination are the reasons behind its non-commercialization.
Its fruits are small, round with red flesh and red seeds. It is early in maturity and TSS is slightly lower than Improved Shipper.
It is an introduction from the USA. It is a medium-vining variety with fruits weighing 4–6kg each. Fruits are round in shape, having bluish bloom on dark green skin and black-green stripes, deep purple, crisp, very sweet (11–13% TSS) flesh and small brown seeds. The fruits ripen 85–90 days after sowing.
Besides, there are a number of extensively cultivated hybrids. They are Madhu Milan, Mohini, MHW 4, MHW 5, MHW 6, MHW 11, MHW 12, MHW 15, NS 246, NS 295, Suruchi, Samtrupti, Amruth and Century 2. Appealing appearance, good quality flesh and transportability and resistance/tolerance to wilt are important characters available in most of these hybrids.
Watermelon is propagated by seed. The seed requirement for planting depend on spacing between plants and rows which again depend on vining habit of the variety. In general, a seed rate of 3.0–3.5kg/ha for small-seeded types and 5.0kg/ha for large-seeded types is sufficient. High-yielding varieties particularly hybrids need about one-third seed rate. They can be transplanted with ball of earth after raising seedlings in alkathene bags. Seeds should be soaked overnight and kept at moist warm place for 48hr for initiation of germination. Pre-germinated seeds could be sown in hills on the raised sides of furrows in upland and in trenches or in pits in the river-beds. Two plants/ hill in trenches or furrows and 4 plants/ pit are retained for growing. A long vining type may require row and plant spacing up to 3.5 and 1.2m in river-beds while medium vining type like Sugar Baby may require 2.0m × 1.0m spacing in upland. Plant-to-plant spacing could further be reduced to 0.6m to accommodate around 16,600 plants/ha if single plant/ hill is retained in place of 2. In pit sowing, pits of 60cm × 60cm size are dug up and filled with soil mixed with sufficient quantity (equal) of organic manure and fertilizer mixture (N + P + K) before sowing.
In north Indian plains, sowing is done during late-February to mid-March while in north-eastern and western India, November–January. In west Bengal, sowing is recommended by mid-November, while in central and south India with mild winters sowing is done during December–January. In Rajasthan, a rainy season crop is also taken and it is sown during August–September. In north Indian hills, Asahi Yamato is sown during April–May. For transplanting, 1–2 seeds/ bag are sown in perforated alkathene bags of 150–200 micron thickness and 8cm × 10cm size. Seedlings at 2–3 leaves stage with ball of earth should be transplanted.
Pruning and training
The excessive vine growth can be pruned manually to restrict vegetative growth and promote higher female : male flower ratio. If apical shoot is pinched and 2–4 side shoots are allowed to grow it gives significantly higher fruit yield than un-pruned plants. This is commonly practised in some parts of the country. Fruit thinning is useful and retaining of 2 fruits/ vine improves fruit size as well as fruit yield.