506 



FUNDAMENTALS OF FRUIT PRODUCTION 



in 1915 only 561, or 17.7 per cent, set fruit in 1916. Five hundred 

 ninety-five flower-bearing spurs of several varieties that set fruit 

 averaged 2.55 grams in weight; 760 flower-bearing non-setting spurs 

 of the same varieties averaged only 1.50 grams in weight. Table 3 shows 

 stiU more clearly the influence of weight of spur on its fruitfulness. In 

 a series of defoliation experiments Heinicke found that though 50.6 per 

 cent of the check spurs set fruit, only 47.6 per cent of those partly defoli- 

 ated and 20.2 per cent of those completely defoliated set. 



Table 3. — Weight op Baldwin Apple Spurs Holding Fruits Varying Lengths 



OF Time 



(After Heinicke^^) 



Evidence Jrom Ringing Experiments. — Certain plants which under 

 ordinary circumstances would not set and develop fruit partheno- 

 carpically have been made to do so by ringing or girdling and thus leading 

 to the accumulation of an extra store of food materials above the injury. 

 Instances of this kind have been recorded in the gooseberry''^ and grape.'* 

 That ringing often does not have such an influence on fruit setting is 

 indicated by certain experiments with Nicotiana.^^^ It is probable how- 

 ever that ringing has quite different effects on various plants and broad 

 generalizations cannot be made from the available data. 



Evidence from Starvation Experiments. — Kusano^^ produced experi- 

 mentally a series of extreme nutritive conditions in an orchid belonging to 

 Gastrodia, at the time of fertilization and during the period of develop- 

 ment of the fruit by partly or completely separating the ovaries from their 

 source of food. Though the results he obtained probably would not 

 apply generally to the developing fruits of other species treated similarly, 

 they are instructive in pointing out some of the relations existing between 

 fruitfulness, sterility and nutritive conditions. The following quotations 

 from Kusano's report summarizes his findings: 



"Imperfect or almost no fruit, but normal seed with embryo: where the 

 normally fertilized flower is separated from its nutritive connection. 



"Imperfect or almost no fruit, and nearly normal but embryoless seed: 

 when the unpoUinated flower is parted from its nutritive connection ; the number 

 of seeds is exceedingly diminished. 



"Imperfect or almost no fruit and seed, but almost normal embryo: when 

 the fertilized flower is subjected to an extremely unfavorable condition of nutri- 



